Produção por fusão seletiva a laser de revestimentos resistentes ao desgaste utilizando a liga Fe68Cr8Mo4Nb4B16

Abstract

Amorphous/crystalline Fe-based alloys are promising materials as protective coatings due to their high crystallization temperatures, high hardness and excellent resistance against corrosion and wear. The application of these alloys as protective coatings can increase the service life of engineering components operating in aggressive environments. Besides presenting interesting combinations between physical and chemical properties, these alloys are economically viable, due to the high content and low cost of Fe. In this context, the present work aimed to investigate the feasibility in producing coatings of composition Fe68Cr8Mo4Nb4B16 %at. by selective laser melting (SLM) from commercially graded precursors. The powders were gas atomized and separated granulometrically for further characterization by scanning electron microscopy (SEM), optical microscopy (MO), x-ray diffractometry (XRD) and differential scanning calorimetry (DSC). In the selective laser melting process, selected powders with particle size between 53 µm and 106 µm were used. The coatings produced by FSL were characterized by XRD, SEM and confocal microscopy (MC). The Vickers microhardness was analyzed on the top of the polished coatings. Tribological tests were performed based on the standard (ASTM G133-05) on polished surfaces (Al2O3 1-µm), in a reciprocal pin-on-plate configuration. The results were divided into three parts: production of powders by gas atomization; production and characterization of SLM coatings and wear resistance of coatings. It was found that Fe68Cr8Mo4Nb4B16 %at. coatings obtained by SLM, using gas atomized powders, have a higher hardness and wear resistance, specific wear rate in the order of 10-5 mm3/Nm, superior the SAE 1020 substrate, specific wear rate in the order of 10-4 mm3/Nm.